Self-adjusting bearing



June 22, 1948. H Q HALL SELF-ADJUSTING BEARING Filed Jan. 24, 1944 INVENTOR. /arg L 17d/Z BY Patented June Z2, 1943 SELF-DJUSTCNG BEARING Harry C. Hall, Phoenix, Ziria, assigner to P. R.

Mallory d: Co., line., indianapolis, Ind., a corporation of Delaware Application January 24, 1944, Serial No. 519,576

(Cl. 30S-71) l Claim.

This invention relates to continuously variable slide-wire inductance devices and has for its object to provide an improved device of this type which is simple in construction and efficient in operation under all conditions of use.

Another object of the invention is to provide a novel carriage structure for an inductive tuner of the above type, including an improved selfadjusting oil-less bearing and associated resilient retaining means for insuring faithful operation under all conditions including extremes of temperature.

Another object of the invention is to provide an inductive tuning device of the type specified having novel and improved details of construction and features of operation.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed,

Slide-wire variable inductance devices are used for tuning radio receivers, oscillators and various other electric and electronic instruments and devices. Generally, they comprise a bare wire coil wound on a suitable insulating form which is mounted on a shaft so as to rotate about its axis. Circuit connection is made to one end of the coil by a contact brush sliding on a suitable slip ring mounted on the end of the coil form and by a sliding contact which slides along the wire of the coil as it is rotated and simultaneously engages a stationary trolley rod mounted alongside the coil form.

The present invention provides an improved mounting for the rotatable coil form of an inductive tuning device of the foregoing type. This novel mounting comprises a self-adjusting oilless bearing for the shaft of the coil form and a special resilient retaining means which permits automatic adjustment of the shaft to compensate for normal wear as well as for variations in the parts due to temperature changes. This improved mounting, in combination with other details of construction hereinafter described, simplifies the construction and maintenance o-f the inductance device and insures its faithful operation under all conditions of use.

Although the novel features which are characteristic of the invention are set forth more in detail in the claim appended hereto, the nature and scope of the invention may be better understood by referring to the following description, taken in connection with the accompanying drawing forming a part thereof, in which a specie embodiment has been set forth for purposes of illustration.

iii)

In the drawing:

Fig. 1 is an end View of a slide'wire variable inductance device embodying the invention, sh'owing the resilient retaining means for the shaft mounting, and other details of construction;

Fig. 21s a side elevation, partly in section, showing the mounting of the coil form and associated elements;

Fig. 3 is an end view opposite to that shown in Fig. 2, illustrating the construction and mounting of the self-adjusting bearing; and

Fig. i is a longitudinal sectional view taken on the line 4--4 of Fig. 2'.

In the following description certain specific v terms are used for convenience in referring to the various details of the invention. These terms, however, are to be interpreted in accordance with the state of the art.

The slide-wire variable inductance device shown in the drawing comprises a pair of spaced parallel end plates Ill and II held in spaced parallel relation by longitudinal spacer rods I2. The unit is customarily enclosed in a suitable metal can shield which is omitted from the drawing in order to simplify the showing. An upstanding mounting flange I3 is formed integrally with the end plate I0 for securing the unit to the panel or apparatus in which it is to be used.

A rotatable control shaft I4 extends axially through end plate I0 and through end plate II, and is adapted to be rotated by asuitable control knob on the end which projects through plate I6). The shaft carries a coil form I5 of tubular insulating material such as resin impregnated ber.

The end plate Ill has a central circular hole formed by an inwardly sloping wall or dish I8 in the shape of a truncated cone, with the small en-d projecting inwardly and being of a diameter substantially larger than that of the rotatable shaft lll. The opposite end plate I I has a circular hole which is in axial alignment with the hole in plate i@ but is only slightly larger in diameter than the shaft I4 so as to make a close running fit with said shaft.

The bearing for the shaft I4 in end plate I0 comprises a pair of complementary bearing blocks 2i' having semi-cylindrical holes which mate, when said blocks are disposed as an annulus about the shaft It, to form a cylindrical bearing surface for said shaft. The outer walls of the bearing blocks 2i are tapered to the same pitch as the conical wall i8 of the opening in end plate I0, so that, when the two halves of the split bearing are seated edge to edge in the cone-shaped wall I8, they cooperate to form a bearing for the shaftI I4. Clearance is provided between the adjacent surfaces of the two blocks 2l to permit selfadjustment to compensate for wear.

Leaf springs 22 are secured to the end plate IIJ by screws 23 and by nuts 24 which hold the spacci' rods I2 in place. The springs 22 are mounted in alignment on opposite sides of the respective bearing blocks 2l, and the free ends 0f said springs are flexed to engage in grooves 25 in th'e outer flat faces of the blocks 2|. It will thus be observed that the springs 22, which need exert but slight pressure, urge the bearing blocks 2| inwardly upon their conical seats and insure a close running t between the mating bearing surfaces of the blocks and the rotatable shaft I4 under all operating conditions. The bearing blocks 2| are preferably made of a suitable insulating material, such as graphitized Bakelite, exerting a minimum friction.

The rotatable shaft I4 extends through the circular hole in end plate II, in axial alignment with the bearing in end plate I0, and makes a close running t with said hole. In the embodiment illustrated, the shaft I4 is provided with annular grooves 27 and 28 on opposite sides of the actual bearing surface 29 of the shaft and therefore on opposite sides of end plate I I. A pair of bifurcated or forked retaining springs 39 are provided with their forks engaging in the respective grooves 2l. and 28 of shaft I4 while the free ends of the forks bear against opposite sides of end plate II and the single bars of said springs have small protuberances or bosses 3I seatedin ahole 32m the plate I I.

The bifurcated retaining springs 39 are identical, and are both flexed outwardly in the same manner, but, since these springs are mounted on opposite sides of end plate iI with their ends bearing against said plate, the two springs act oppositely and equally upon the shaft I4. That is, one spring 30 tends to urge the shaft I4 axially toward the left as viewed in Fig. 4, while the other spring 39 tends equally to urge said shaft toward the right, with the result that the bear ing surface 29 of the shaft maintains the proper running fit in the hole of end plate II while permitting slight end play. This construction insures automatic adjustment of the shaft under all operating conditions and prevents freezing even at extremely low temperatures.

A bare wire coil 34 is wound on the surface of the tubular coil form I5. If desired, the form may be provided with a shallow groove in which the wire 34 is wound. Coil 34 may suitably be made of hard drawn copper wire plated with silver, and, if desired, coated `with a protective lubricant. The ends of the coil 34 are soldered to metal discs or rings 35 and '36 secured to the respective ends of the coil form. The contact ring 35 is engaged by a contact spring 3'! which is connected to a terminal -38 to provide an external circuit connection. Contact ring 36 is engaged by a fork-shaped contact spring 39 secured to a bracket 4I) of conducting material. A trolley rod 42 of conducting material is secured to the bracket 49 and to the inner end of a terminal -43 which extends outwardly for an external connection.

A tubular stop member 44 is slidably mounted on the trolley rod 42, and a sliding contact member 45 is mounted on said trolley rod beneath the stop member 44 so as to slide therewith. The sliding contact member 45 has two longitudinally grooved nibs 46 resting upon the wire of coil 34 at two spaced points thereon with the grooves of said nibs engaging said wire. The Contact member 45 is originally bent suiciently to provide the necessary spring pressure on the nibs y4t when the member is interposed between the rod 42 and the coil. As the shaft I4 rotates the coil form I5, the nibs 46 slide along the wire 34 and move the contact member 45 and the stop member 44 along rod 42. In the embodiment illustrated, the portion of coil 34 to the left of contact member 45, as viewed in Fig. 2 is short circuited by the contact member 45, trolley rod 42, bracket 4I), spring 39 and disc 36. Suitable stop members 4I may be provided adjacent opposite ends of the coil form I5 for engagement with the sliding stop member 44 to arrest the movement of the coil form before the Contact member 45 reaches either end of the coil 34.

While the present invention, as to its objects and advantages, has been described herein as carried out in specic embodiments thereof, it is not to be limited thereby but is only to be restricted in accordance with the spirit and scope of the appended claim.

What is claimed is:

A bearing for a variable inductance device comprising a support having an inwardly sloping tapered wall portion defining a frustro-conical passage, a shaft extending through said passage, a pair of complementary bearing blocks disposed within said passage, the inner walls of said bear REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 190,048 Jennings, Sr. Apr. 24, 1877 1,186,839 Roy June 13, 1916 1,542,190 Traylor June 16, 1925 1,545,829 Herschel July 14, 1925 1,998,728 Marles Apr. 23, 1935 2,163,647 Ware June 27, 1939 2,260,877 Ware Oct. 28, 1941 2,295,348 Leach Sept. 8, 1942 2,331,522 1943 Vance Oct. l2, 

